The present invention relates to a rotary compressor and, more particularly, to a reliable, extremely high pressure ratio, high efficiency, and lightweight sliding-vane rotary-compressor which has application in heat pump, air conditioning, and refrigeration (vapor-compression) applications as well as for the compression of other fluids such as air, nitrogen, and argon. The compressor can be configured as a lubrication-free device utilizing self-lubricating materials or as an oil lubricated device with very high compression ratio capability.
Conventional vane compressors have a relatively low pressure capability, i.e. somewhere in the range of 65 psi. Moreover, these compressors have insufficient volumetric and overall thermal efficiency for use in today's environment where high efficiency components are necessary for heat pumps, refrigeration equipment and air-conditioning units. Also, the conventional compressors are not completely compatible with the newer, environmentally safe refrigerants such as R-134a.
In applications such as aircraft or electronics cooling systems where low weight, small size, reliability, and efficiency are important criteria, as well as in refrigerant recovery apparatus where stringent thermal requirements exist, both the conventional sliding-vane compressors and other types of compressors such as reciprocating compressors are unacceptable. The conventional vane compressors do not provide adequate pressure ratio, and the other types of compressors are too heavy and are also difficult to obtain a high pressure through one stage. Moreover, the reciprocating compressors have considerable intake losses (pressure drop) and large reciprocating acceleration forces that result in rough operation of the compressor. This kind of compressor also require a relatively large starting torque and hence a large motor.
It is, therefore, an object of the present invention to develop a lightweight, high compression ratio rotary compressor to overcome or eliminate the problems and disadvantages associated with both conventional vane compressors and the other types of compressors, particularly those compressors designed for use in compact cooling and refrigerant recovery application where extreme high pressure ratio exists.
It is another object of the present invention to provide compressors, particularly sliding-vane rotary compressors, configured adequately to solve the problems of frictional heat, internal leakage, and low pressure capacity encountered in conventional rotary compressors.
It is a further object of the present invention to configure a sliding-vane rotary compressor which maximizes compression ratio, flow rate, and thermodynamic and volumetric efficiency.
Yet another object of the present invention is to provide a structurally simple sliding-vane rotary compressor, especially useful in micro-climate cooling systems and refrigerant recovery systems, which is lightweight, reliable, adaptable to unusual thermal requirements, smooth running, and operable with small initial starting torque.
Still a further object of the present invention is to configure a sliding-vane rotary compressor that is particularly suitable for high compression ratio of more than 100:1 in one stage.
The foregoing objects and advantages of the present invention have been achieved with a sliding-vane rotary compressor having an improved bore geometry, vane slot arrangement, valve assembly, and injected lubrication sealing effects which permit, by way of example, gas or vapor to be drawn at low pressure (say, 2.5 psia) and discharged at high pressure (say, 365 psia) in one stage.
The bore geometry of the rotary compressor of the present invention is such that the curvature used is neither a single circle nor a single ellipse, as in conventional rotary compressors. In the present invention, the outline of the bore has been configured, through a computer program, to have the best mechanical and thermodynamic performance, i.e., to maximize the inlet flow in the inlet area and maximize the compression ratio in the compression area, to minimize the dead volume and keep low exhaust resistance, to minimize the internal leakage and maximize the volume efficiency, to minimize the frictional heating, and, to increase thermodynamic efficiency.
A sliding-vane rotary compressor incorporating the features of the present invention has the following advantages:
1. Much higher pressure capability, up to about 450 psi or more as compared with conventional vane compressors with pressure capability of only 65 psia;
2. Extremely high compression ratio;
3. Improved volumetric and overall thermal efficiency;
4. Improved internal sealing because of the sealing effect of injected lubricant resulting in high volumetric flow rates as well as the aforementioned high pressure capability and high pressure ratios;
5. Low friction resulting in reduced wear, increased life, less frictional heat, and high efficiency;
6. Compact size; and
7. Compatibility with all refrigerants including the more environmentally safe refrigerants.